This invention relates generally to a ride control system for a machine and more particularly to a control system for selectively locking a suspension system.
In known ride control systems for machines, cushioning of the ride is controlled by suspension systems employing a damper between the load bearing frame and the ground engaging wheels to absorb the effects of impact as the machine engages the ground. Machines are often provided with attachments such as a bucket, for example, to perform work on external concerns. In preparation for performing work with the attachment, an operator maneuvers the attachment and thereafter performs the desired operation. However, controllability of the attachment is limited by the suspension system which remains reactive when the operator is attempting to position the attachment. For example, the machine may lurch or settle as the attachment is maneuvered resulting in an inefficient performance of the operation or a failed attempt to perform the desired operation.
It is known to provide suspension override capabilities to stabilize a rebounding wheel, however this instrumentation is typically complicated and consequently expensive to implement. Additionally, this system requires a significant number of fluid transfer components, and accordingly, system leaks are a concern. Even a slight leak may render the system inoperable.
For example, U.S. Pat. No. 4,971,353 issued to Buma et al. discloses an accumulator in fluid communication with an actuator through a shut-off valve and a flow resistance. An auxiliary accumulator is connected directly to the actuator to serve as an additional spring in the event a wheel experiences a significant and rapid rebound. The suspension control system slows movement of a piston rod of the actuator by controlling a fluid condition at the site of the rod end, while at the same time, the head end of the actuator is in fluid communication with the auxiliary accumulator through a restriction. Since the actuator remains in continuous fluid communication with the accumulator, fluid transfer between the actuator and accumulator is not effectively blocked.
It is desirable to provide a suspension control system of simple construct to improve the controllability of the attachment. Further, a suspension control system configured to selectively lock-out the suspension system without a significant addition of fluid transfer components which may otherwise leak and render inoperable the lock-out system is desirable.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention a suspension control system is provided and adapted for use in a fluid system of a machine and includes a locking circuit disposed between a moveable element and an accumulator which is selectively activatable to sustain a load support member in a fixed position relative to a base member. The suspension control system includes the load support member, the base member and a moveable element attached to the base member and the load support member. The load support member is moveable relative to the base member through the moveable element. An accumulator is in fluid communication with the moveable element and a locking circuit is disposed between the moveable element and the accumulator and is selectively activatable to sustain the load support member in a fixed position. The locking circuit includes a pressurized fluid supply and a flow blocking mechanism operably engaged with the pressurized fluid supply. The flow blocking mechanism is urged to block fluid communication between the moveable element and the accumulator when the locking circuit is selectively activated.
In another aspect of the invention a method for stabilizing an implement of a machine subject to an external influence is provided and includes the steps of accumulating pressurized fluid provided by an accumulator in fluid communication with a moveable suspension member in response to the external influence exerted on the machine; directing the pressurized fluid to a lock-out circuit disposed between the accumulator and the moveable suspension member; and causing the accumulator and the moveable element to be fluidly disconnected, wherein cushioning effects of the accumulator are disabled.